Infection with Panton-Valentine Leukocidin–Positive Methicillin-Resistant Staphylococcus aureus t034

Panton-Valentine leukocidin (PVL)–positive methicillin-resistant Staphylococcus aureus (MRSA), sequence type 398 is believed to be of animal origin. We report 2 cases of infection due to PVL–positive MRSA, spa type t034, in patients in Sweden who had had no animal contact

Enterohemorrhagic Escherichia coli, EHEC.Microbiological diagnosis, characterisation and clinical bacteriological aspects

Enterohemorrhagic Escherichia coli (EHEC) constitutes a group of E. coli that in the past two decades has been the cause of several outbreaks of gastrointestinal disease. The microorganism causes hemorrhagic colitis (HC) and haemolytic uremic syndrome (HUS) in 5-10% of the patients, 30% of the HUS patients develop remaining kidney injuries. The capacity to control EHEC disease and to limit the scale of outbreaks is dependent upon prompt diagnosis and identification of the source of infection. Cattle are the principal reservoir of EHEC and foodstuffs, which presumably have come into contact with domestic animal manure and/or are inadequately pasteurised, are important vehicles of infection. The predominating virulence factor of EHEC is the verocytotoxin first identified in an E. coli of serogroup O157:H7. In the present study, the PCR technique with primers detecting the verocytotoxin genes was shown to be a fast, sensitive and specific method to screen for and identify EHEC. The study contributes to the knowledge and understanding that also EHEC non-O157 are pathogenic and that all verocytotoxin producing E. coli should be looked after among patients with diarrhoea, HC and HUS. The importance of quick identification was exemplified in an outbreak of EHEC among the staff at the children s hospital in Göteborg, Sweden. As the outbreak was promptly identified, partly thanks to the PCR technique, no further spread to other staff members or patients occurred. In the present thesis, pulsed-field gel electrophoresis (PFGE) was used and the method was shown to be very useful in the epidemiological work to separate single cases of EHEC from outbreaks. In order to further characterise EHEC non-O157, the presence of additional chromosomal and plasmid genes probably involved in the pathogenesis were analysed as these genes have been found in EHEC O157. The gene coding for intimin, enabling tight attachment to epithelial cells of the intestine was also often present among EHEC non-O157. Moreover, the gene coding for an enterohemolysin possibly supporting the bacterial need for iron was especially often present among EHEC isolated from patients with severe symptoms. Further, the study has shown that the gene coding for aerobactin seems to be able to compensate for the absence of enterohemolysin and that also the type 1 fimbriae may be valuable to obtain a niche in the gut. A comparative study of verocytotoxin producing E. coli in cattle showed that there is a significantly lower amount of E. coli harbouring the intimin gene and the gene coding for aerobactin, supporting the assumption that not all verocytotoxin producing E. coli in cattle are pathogenic. In conclusion, methods identifying the verocytotoxines or their genes should be used to identify EHEC of all serogroups. PCR is preferable as it is a fast, sensitive and specific method. Genes coding for intimin, enterohemolysin and aerobactin adds to the pathogenicity of EHEC. These genes are not that common among isolates from cattle. PFGE is a most valuable tool for epidemiological tracing of EHEC

Sub-typing of extended-spectrum-β-lactamase-producing isolates from a nosocomial outbreak: application of a 10-loci generic Escherichia coli multi-locus variable number tandem repeat analysis.

Extended-spectrum β-lactamase producing Escherichia coli (ESBL-E. coli) were isolated from infants hospitalized in a neonatal, post-surgery ward during a four-month-long nosocomial outbreak and six-month follow-up period. A multi-locus variable number tandem repeat analysis (MLVA), using 10 loci (GECM-10), for 'generic' (i.e., non-STEC) E. coli was applied for sub-species-level (i.e., sub-typing) delineation and characterization of the bacterial isolates. Ten distinct GECM-10 types were detected among 50 isolates, correlating with the types defined by pulsed-field gel electrophoresis (PFGE), which is recognized to be the 'gold-standard' method for clinical epidemiological analyses. Multi-locus sequence typing (MLST), multiplex PCR genotyping of bla CTX-M, bla TEM, bla OXA and bla SHV genes and antibiotic resistance profiling, as well as a PCR assay specific for detecting isolates of the pandemic O25b-ST131 strain, further characterized the outbreak isolates. Two clusters of isolates with distinct GECM-10 types (G06-04 and G07-02), corresponding to two major PFGE types and the MLST-based sequence types (STs) 131 and 1444, respectively, were confirmed to be responsible for the outbreak. The application of GECM-10 sub-typing provided reliable, rapid and cost-effective epidemiological characterizations of the ESBL-producing isolates from a nosocomial outbreak that correlated with and may be used to replace the laborious PFGE protocol for analyzing generic E. coli

Clinical severity of Mycoplasma pneumoniae (MP) infection is associated with bacterial load in oropharyngeal secretions but not with MP genotype.

BACKGROUND: Disease severity in Mycoplasma pneumoniae (MP) infection could potentially be related to bacterial factors such as MP genotype (MP1 or MP2; distinguished by different adhesions proteins) or bacterial load in airway secretions. We have compared these parameters in patients who were hospitalized for MP pneumonia, with outpatients with mild MP disease. METHODS: MP bacterial load was measured by real-time PCR in 45 in- and outpatients ("clinical study group") in whom MP DNA had been detected in oropharyngeal secretions by PCR. In addition, genotype and phylogenetic relationships were determined. The phylogenetical assessment was done by partial DNA sequencing of the P1 gene on isolates from 33 patients in the clinical study-group where sufficient DNA was available. The assessment was further extended to isolates from 13 MP-positive family members and 37 unselected MP positive patients from the two subsequent years and two different geographical locations. In total 83 strains were molecular characterized. RESULTS: Mean MP loads were significantly higher in 24 hospitalized patients than in 21 outpatients (1600 vs. 170 genomic equivalents/microL, p = 0.009). This difference remained significant after adjustment for age and days between disease onset and sampling. Hospitalized patients also had higher C-reactive protein levels. Mean levels were 188 vs 20 mg/L (p = 0,001). The genotype assessment showed MP genotype 1 in 17 of the 33 sequenced strains from the clinical study-group, and type 2 in 16 of these patients. Within each genotype, sequence differences were minimal. No association between disease severity and MP genotype was observed. In the extended genotype assessment, MP1 was found in similar proportions. In family contacts it was found in 53% and among patients from the two subsequent years 53% and 40%. CONCLUSIONS: A higher MP bacterial load in throat secretions at diagnosis was associated with more advanced respiratory disease in patients, but MP genotype did not influence disease severity. Both MP genotypes co-circulated during recent outbreaks in Sweden

Genetic Profiling of Enterohemorrhagic Escherichia coli Strains in Relation to Clonality and Clinical Signs of Infection

Sixty-seven human strains of enterohemorrhagic Escherichia coli (EHEC) (from patients with more or less severe symptoms) were serogrouped and arranged according to pulsed-field gel electrophoresis (PFGE) patterns. We used PCR to investigate the strains according to known or putative virulence factors, and associations with disease were studied. All EHEC strains with the same PFGE pattern belonged to the same serogroup. On the contrary, two serogroups (O157 and O8) included strains with different PFGE patterns. We found several different combinations of chromosomal and plasmid-borne determinants, encoding the putative virulence factors, among the strains. As judged from clinical symptoms, there was no marked difference in pathogenicity among the strains and their combinations of virulence traits. All strains of O157 had the genes coding for verocytotoxin (VT) 2, intimin (eaeA), E. coli hemolysin (E-hly), and secreted serine protease (espP). Among EHEC non-O157 strains, the genes coding for VT1 and VT2 were equally dispersed. EaeA positivity was just as common among VT1- as VT2-positive strains. Among the plasmid-borne determinants, E-hly and espP were the most common and E-hly might be a pathogenicity marker among EHEC non-O157 strains. The conclusion is that PFGE is a very useful tool in epidemiological studies. The EHEC plasmids are heterogeneous in their gene composition, with the four plasmid-borne determinants found in many combinations. There was no reliable correlation between chromosomal and plasmid-borne virulence factors and human disease

First Case of Human “Candidatus Neoehrlichia mikurensis” Infection in a Febrile Patient with Chronic Lymphocytic Leukemia ▿

An immunocompromised patient presented with febrile episodes, an erysipelas-like rash, and thromboembolic complications. Amplification of 16S rRNA gene sequences from blood and sequence analysis revealed “Candidatus Neoehrlichia mikurensis.” We report the first case of human disease caused by “Ca. Neoehrlichia mikurensis.